Transmission #03

Re:load Pro, an Open Source Active Load


Open source test equipment has to be one of the best gifts open source hardware has given back to the community. Nowhere is this more true than in the case of  [Nick's] Re:Load Pro over on Kickstarter. Unlike resistors or similar dummy loads, an active load will always draw the set amount of current regardless of voltage. Active loads are often used to test power supplies and batteries. Is that 2500 mAh LiPo battery overstating it’s capacity? Can the power supply you just designed handle 2.5A at 12V? Both of these are jobs where active loads would come in handy.

The Re:Load Pro is actually the third version of the Re:Load. [Nick] designed the original Re:Load after becoming frustrated at the lack of a cheap active load for testing a power supply. Plenty of people showed interest in the Re:Load, but they wanted more features. That’s where the Re:Load Pro comes in. More than a straight analog design, the Pro has a Cypress PSOC 4 Arm Cortex M0 processor running the system.

[Nick] and his company, Arachnid Labs, are no strangers to us here at Hackaday. When we last covered [Nick], he was asking the USB Implementers Forum about a low cost Vendor ID option for open source hardware projects. Fittingly, the Re:Load Pro is an open source project. The schematics and source code are available on Github.

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Building the Internet of “Thing” at FTF2014

It’s official: all the hype around IoT is starting to get a bit annoying. Not because there’s anything wrong with building Internet-connected devices, but because so many people are trying to jump on the bandwagon with the same old “Future: brought to you by Megacorp #07″-mindset. Recycled visions of estranged professionals, with their homes, offices, business meetings and hotel rooms, all powered by the latest “one IoT platform to rule them all” – are back on. Even though the mythical “Smart” refrigerator didn’t changed the world back in 2001, I guess that there’s no harm in trying it again. After all, we have seen this working out great in software, with redos of dot-com era ideas turning into massive successes a decade later.
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Building a Mesh Networked Conference Badge

[Andrew] just finished his write-up describing electronic conference badges that he built for a free South African security conference (part1, part2). The end platform shown above is based on an ATMega328, a Nokia 5110 LCD, a 433MHz AM/OOK TX/RX module, a few LEDs and buttons.

The badges form a mesh network to send messages. This allows conversations between different attendees to be tracked. Final cost was the main constraint during this adventure, which is why these particular components were chosen and bought from eBay & Alibaba.

The first PCB prototypes were CNC milled. Once the PCB milling was complete there was a whole lot of soldering to be done. Luckily enough [Andrew]‘s friends joined in to solder the 77 final boards. He also did a great job at documenting the protocol he setup, which was verified using the open source tool Maltego. Click past the break to see two videos of the system in action.

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Homemade Gravity Light Doesn’t Last Long but Proves the Concept!

gravity light

After being inspired by the Deciwatt Gravity light, [Steve Dufresne] decided he wanted to try making his own as a proof of concept.

The Gravity Light by Deciwatt is an innovative device designed for third world countries to help eliminate expensive lighting like kerosene lamps. It has a small weight on a pulley which can be lifted up in under 3 seconds. During its slow descent down the weight provides light for 25 minutes! It’s affordable, sustainable, and reliable. It’s also mechanically impressive, which is exactly why [Steve] decided to try making his own.

He’s using a single LED, a small DC motor, a few pieces of wood, an old bicycle wheel, some bicycle chain, and a few jugs of water. The water is connected to the chain which is looped over the smallest gear on the bike. The generator is then powered by a belt wrapping around the outside of the rim. This gives the motor enough speed to generate electricity for the LED. His current design only lasts for about 3 minutes, but he’s already working on the second iteration. Testing systems like this really give you an appreciation for the effort that must have gone into the real Gravity Light.

Stick around after the break to see it in action.

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Inkjet Transfers to Wood

Color Image on wood board

You can’t feed a piece of wood through a stock inkjet printer, and if you could it’s likely the nature of the material would result in less than optimal prints. But [Steve Ramsey] has a tutorial on inkjet transfers to wood over on his YouTube Channel which is a simple two-step method that produces great results. We really love quick tips like this. Steve explains the entire technique while creating an example project – all in under 2 minutes of video. We don’t want to get your hopes up though – this method will only work on porous absorbent surfaces like bare wood, not on PC boards. We’ve featured some great Inject PCB resist methods here in the past though.

The transfer technique is dead simple. [Steve] uses the backing from a used sheet of inkjet labels (the shiny part that normally gets thrown away). He runs the backing sheet through his inkjet printer. Since plastic coated backing sheet isn’t porous, the ink doesn’t soak in and dry. He then presses the still wet page onto a piece of wood. The wet ink is instantly absorbed into the wood. A lacquer clear coat seals the image in and really make the colors pop. We’d like to see how this method would work with other porous materials, like fabrics (though the ink probably wouldn’t survive the washing machine).

Click past the break for another example of [Steve's] work, and two videos featuring the technique.

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The HellZXchreiber


Hellschreiber – German for ‘light pen’ – was developed in the 20s as a way to transmit text in a way that was much more robust than the teletypes of the time. These devices were used to great effect by the Germans in WWII, and later became popular with wire services and was used until the 80s. The fax machine then happened, and no one really cared about Hellschreiber, save for a few plucky amateur radio enthusiasts.

In the early 90s, a few of these amateur radio enthusiasts realized they could use their personal computers to communicate with this extremely simple protocol that’s also very resilient against interference and weak radio links. [Danjovic] is following in their footsteps by decoding Hellschreiber on an old ZX Spectrum clone.

[Danjovic] tested his code with the sound sample found in the Hallschreiber wiki article and some text generated by Fldigi. Everything works beautifully, an [Dan] can even change the intensity of the text with the volume control – a very useful feature should the HellZXchreiber ever make it out into the field.

Source and image files available for all you strange Speccy fans. Everyone else can check out the videos below.

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Frozen Instruments Played at Swedish Music Festival


[Tim Linhart] wanted to do something different for this Swedish music festival — so he decided to carve all the instruments by hand, out of ice.

The festival consists of seven bands playing very different musical styles, with over 40 concerts occurring during the festival. [Tim Linhart] has painstakingly carved each instrument from violins to cellos out of individual sheets of ice. He adds strings and fret-boards to complete each piece, and if the temperature goes above zero it’s game over. The concerts are held in a building made of ice to make sure this doesn’t happen.

And since they are built out of layers — he’s also thrown in some RGB LEDs to give the instruments a bit more pizzazz. They actually sound pretty good too!

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